Igniter cartridge



ug- 21, l956 A. l.. HlTcHENs ETAL 2,759,419

IGNITER CARTRIDGEy Filed Aug. 20, 1952 2 Sheets-Sheet l Aug. 21, 1956 A. l.. Hl'rcHENs ErAL 2,759,419

IGNITER CARTRIDGE Filed Aug. 20, 1952 2 Sheets-Sheet 2 United States Patent O "f IGNITER CARTRIDGE Aaron L. Hitchens, North Haven, and Harold Edward Perkins, Jr., Hamden, Conn., assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia Application August 20, 1952, Serial No. 305,436

Claims. (Cl. 102--39) This invention relates to igniter cartridges in general, and to fuel igniter cartridges for the engines of jet planes in particular.

While the engines of jet planes are equipped with electric ignition systems for engine-lighting purposes, these electric ignition systems have at times failed to reignite the fuel mixtures in jet engines after so-called llameouts thereof occurred. A flame-out of a jet engine in a plane, i. e. occasional uncontrolled extinction of the engines flame and consequent stalling of the jet engine, may well have disastrous consequences for the plane if in ight, and may even endanger the pilot of the plane or other passengers thereon, unless the engine can be retired While the plane is still in the air.

Accordingly, it is the primary object of the present invention to provide an igniter cartridge of a type which, when fired, will issue a flame of sufficient heat intensity and duration to ignite or re-ignite a fuel charge under the various conditions prevailing in the combustion chamber of a jet engine of a plane at ground level or within a wide range of altitudes.

It is another object of the present invention to provide an igniter cartridge of this type which may readily be chambered in suitable tiring equipment on a jet engine of a plane, and which may be red, by remote control and at the will of the pilot or other authorized personnel of the plane, so that the llame issuing from the fired cartridge will be directed into the combustion chamber of the engine and ignite the fuel charge therein.

It is a further object of the present invention to provide an igniter cartridge of this type which, on tiring, will issue not only a llame of very hot gases and any other products of combustion from the burning cartridge charge, but also a multitude of relatively large globules of molten metal which, on burning in the combustion chamber of a jet engine, transmit such intense heat to the immediately surrounding portions of the fuel-air charge therein that the same pre-ignite and, together with the ame from the cartridge, ignite the remainder of the fuel-air charge.

Another object of the present invention is to provide in an igniter cartridge of this type a flash tube which, besides serving its customary function of directing the ash from the primer of the cartridge to a readily ignitable charge in the front end of the cartridge for the ignition thereby of the less readily ignitable main burning charge therebetween, is made of a metal which, on subjection to the surrounding ame from the main charge, will melt off in relatively large globules that are carried by the ame from the cartridge into the combustion chamber of a jet engine for the aforementioned pre-ignition of portions of the fuel-air charge therein and the almost simultaneous ignition of the rest of this fuel-air charge.

A further object of the present invention is to provide an igniter cartridge of this type which may not only be handled safely under all normal conditions, but which will fail to tire on its own accord and not become damaged or undergo changes conducive to misring, when subjected 2,759,419 Patented Aug. 2l, 1956 ICC .to occasional shock or vibration, or rapid acceleration or deceleration, by a jet plane in flight.

It is another object of the present invention to provide an igniter cartridge of this type of which the shell may conveniently and economically be in the form of a paper shell in which the main burning and ignition charges may, by reason of the beforementioned provision of a metal ash tube therein, be compacted under relatively high pressure without damaging or even weakening the shell, so as to assure a uniform loading density of the charge that will produce a uniform flame of the desired duration.

Further objects and advantages will appear to those skilled in the art from the following, considered in conjunction With the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. l is a diagrammatic, part-sectional illustration of a jet engine having firing equipment for an igniter cartridge of the present invention;

Fig. 2 is a diagrammatic illustration of a jet engine similar to Fig. l, but showing the igniter cartridge in the performance of its designated function;

Fig. 3 is an enlarged side view of an igniter cartridge embodying the present invention;

Fig. 4 is a longitudinal section through the same cartridge;

Fig. 5 is an enlarged side view of a prominent part of the instant igniter cartridge, to wit a ash tube thereof;

Fig. 6 is an end View of the ash tube as seen in the direction of the arrow 6 in Fig. 5;

Fig. 7 is a fragmentary longitudinal section through an end of the flash tube prior to its closure;

Figs. 8 and 9 are enlarged fragmentary sections taken on the lines S-S and 9 9, respectively, of Fig. 6; and

Fig. l0 is an enlarged fragmentary section through the closed end of the ash tube, showing the application of a seal thereto.

Referring to the drawings, and more particularly to Figs. 3 and 4 thereof, the reference numeral 20 designates an igniter cartridge which comprises a shell 22 carrying a primer 24 and containing an ignition charge 26 and a burning charge 28. The cartridge 20 further comprises a flash tube 30 which is presstted or otherwise secured in the usual primer cavity 32 in the head 34 of the shell 22 and extends coaxially of the latter. The burning charge 28 extends in the shell 22 between base and bottom wads 34 and 35 on the one hand and the ignition charge 26 on the other hand, while the ignition charge 26 extends to a top wad 36 Which is securely held in place by the adjacent crimped-over end 38 of the shell.y The' head 40 of the flash tube 30, which is directly mounted in the primer cavity 32 of the shell head 34, is diametrically enlarged for the reception of the primer 24.

The instant cartridge 20 is adapted primarily, though not exclusively, for igniting the fuel-air mixture in a jet engine and especially re-igniting the same after a flameout and under all conditions in which the conventional electric ignition system will at times" fail to re-ignite the mixture. Figs. l and 2 show diagrammatically the combustion chamber 42 of a jet engine which may be considered to be installed in a plane. Fuel is forced from an injector nozzle 44 into the combustion chamber 42 and compressed air is admitted through the inlet 46 thereof to mix with the injected fuel charge and form therewith a combustible mixture. Mounted on the engine is suitable equipment 48 for chambering an igniter cartridge 2li of the instant kind. The equipment 4S includes a firing pin 50 which, on actuation of a trigger 52 by remote control at the will of the pilot or other authorized personnel of the plane, is released to lirel the chambered cartridge in the manner indicated in Fig. 2. The tired cartridge is adapted to issue a hot flame f of several seconds duration into the combustion chamber 42 and ignite the fuel-air mixture therein.

The shell 22 may conveniently and economically be a paper shell, like or similar to a shotshell, and carry the usual brass head 34. If desired, the shell 22 may also be made of metal and formed integrally with the head 34. The primer 24 may be like or similar to a conventional shotshell primer. The burning charge 28 in the cartridge 20 is preferably selected to produce a ame of sufficient heat intensity ordinarily to ignite the fuel-air mixture in the combustion chamber of a jet engine. In the present instance, the burning charge 28 preferably consists of a less readily ignitable but slow-burning major base charge 56 and a faster-burning intermediate or transition charge 58 which is more readily ignited by the ignition charge 26 and produces a ilame of suiiicient heat intensity and duration to ignite the base charge 56. While the several charges 26, 56 and 58 may be of many different compositions suited for the intended purpose, outstandingly snccessful results with respect to ease of assembly and smooth and effective functioning have been obtained by the provision of a transition charge 58 consisting of a blend of the slow-burning base charge 56 and the fast-burning ignition charge 26.

For example, the base charge 56 may be of the following composition: about 25% by weight of powdered magnesium; about 60% by weight of an oxidizing agent in powder form, such as alkaline earth peroxide or nitrate, with the remainder being smaller percentages by weight of fuels, such as oxalates, and binders, such as metal soaps, for example calcium resinate.

For the subsequent preparation of the intermediate and ignition charges 58 and 26, the following ignition mixture may be formed: about by Weight of powdered magnesium, and about 85% by weight of an alkaline earth peroxide and small amounts of insoluble metal soaps.

The intermediate charge 58 is preferably composed of a blend of about 80% by weight of the above-specified composition of the base charge 56, and about by weight of the above-specified ignition mixture, while the ignition charge 26 may be composed of about 80% by weight of the above-specified ignition mixture and about 20% by weight of the composition of the base charge 56.

In firing the instant cartridge, the ash from the primer 24 will pass through the lash tube 30 and burst open the closed end 60 of the latter to set off the surrounding ignition charge 26 which will immediately ignite the intermediate charge 58, and the latter will, in turn, ignite the base charge 56. The intermediate charge 58, while burning slower than the ignition charge 26, nevertheless burns sutiiciently fast to ignite the base charge 56 almost instantaneously. It is this base charge 56 which burns considerably slower than the other charges and which lends to the cartridge flame its desired duration of several seconds, say between 4 and l0 seconds, for instance.

In accordance with an important aspect of the present invention, the ash tube 30 is made of a combustible metal which, on subjection to the ame in the cartridge and more particularly to the enduring flame from the base charge S6, will melt to a state where the flame will carry off the molten metal in the form of relatively large globules or chunks. Metals suitable for this purpose may, for example, be aluminum, magnesium, zinc, or alloys containing more than 50% of any one or more of these metals. These globules of molten metal, which are thus carried in dispersed fashion by the cartridge flame into the combustion chamber of the jet engine, will burn in the fuelair mixture therein and constitute hot spots which in heat intensity surpass the cartridge flame and easily ignite the immediately surrounding portions of the fuel-air mixture. Thus, even if the cartridge flame is sufficiently hot to ignite the particular fuel-air mixture prevailing at the time in the combustion chamber of the jet engine, the presence of the globules of molten metal in the cartridge flame gives additional assurance for the unfailing and quick ignition of the fuel-air mixture. On the other hand, if the fuel-air mixture in the combustion chamber of a jet engine should, after a flame-out of the latter in the air, be qualitatively such as to oppose its ready ignition by the cartridge flame alone, the burning globules of molten metal in the ilame will pre-ignite the immediately surrounding portions of the fuel-air mixture, and these pre-ignited portions of the mixture, together with the flame from the cartridge, will forthwith ignite the remaining fuel-air mixture.

it has been mentioned hereinbefore that the globules of molten metal carried away by the cartridge flame are relatively large in size. In any event, these globules are larger in size, and preferably considerably larger, than the granules of powdered metals which are sometimes added to cartridge charges. There are otherwise no fixed limits as to the permissible sizes of these globules in the flame of a cartridge of this type. While the globules of molten metal in the iiame of any given cartridge will vary in size, the average size of the globules in the cartridge tiame will largely be determined by the melting point of the metal of the ash tube and the intensity of the heat of the cartridge llame. For satisfactory results in any event, the metal of the iiash tube and the burning charge in the cartridge may be selected so that the globules or chunks of molten metal carried off by the cartridge flame are not only relatively large in size, but are also Well dispersed in the cartridge flame. Thus, cartridges of this type with ignition and burning chargesI like or similar to those specifically mentioned hereinbefore, and with ash tubes of aluminum, have been used successfully for the easy and quick re-ignition of the fuel-air mixtures in jet engines after ame-outs thereof.

As previously mentioned, the base charge 56 is in any event slow-burning an-d, hence, somewhat difiicult to ignite quickly with the usual ignition charge. lt is for this reason that the provision of the intermediate or transition charge 53 between the slow-burning base charge 56 and the fastburning ignition charge 26 .is significant, in that the transition charge in effect continues the necessarily brief flame of the ignition charge in the form of a iiame which is not only of considerably longer duration, but has also greater heat intensity, than the flame of the ignition charge. As a result of the provision of the transition charge, the ignition of the slow-burning base charge is more uniform since the iiame of the transition charge engulfs greater depth of the base `charge than would the flame of the ignition charge, causing thereby instantaneous and maximum ignition of the base charge and, accordingly, an irnmediate flame of sufficient heat intensity ordinarily to ignite a fuel-air mixture. in this connection, the blending of the transition and ignition charges from different proportionate amounts of the base charge and a special ignition mixture is of further significance in that all charges have common constituents that will result in a smooth, progressive and rapid propagation of the ame from the ignition charge to the slow-burning base charge.

The flash-discharge end of the flash tube 30 may originally be open as at 62 (Fig. 7), and the same is thereupon closed by simply crimping or otherwise deforming equal peripheral wall portions 64 of the tube end inwardly in such fashion (Figs. 6, 8 and 9) that they become folded upon each other and assume the appearance of a plurality of equiangularly spaced radial ns 66, in this in stance three. In closing the discharge end of the flash tube conveniently and economically in this manner, the folded-over wall portions of the tins 66 may readily be unfolded by the primer flash, yet will effectively block over a considerable distance any penetration into the flash tube of particles of the surrounding compacted ignition charge 26 before the cartridge is fired. To seal even minute gaps g between the folded-over wall portions of any of the radial tins 66, the closed end 60 of the flash tube 30 may conveniently be dipped in a suitable sealing agent, such as lacquer l, for instance, of which a small amount will be drawn by capillary attraction into these gaps and subsequently dry therein (Fig.

The hereinbefore described closure of the liash-discharge end of the ash tube 30 is not only exceedingly simple and nevertheless secure for the purpose in mind, but the same will be opened from the center outwardly (Fig. 6) under the compulsion of the flash from the primer 24, assuring thereby even burning of the ignition charge 26 on all sides of the ash tube 30 and, accordingly, even ignition of the remaining charges 58 and 56 for a most effective and uniform flame from the cartridge. The ready opening of the closed discharge end 60 of the ash tube from the center thereof by the flash from the primer is due to the fact that the folded-over wall portions of the radial tins 66 offer the least resistance to unfolding at their common center x (Fig. 6).

The provision in the instant cartridge of a ash tube of metal is of further advantage in that it permits the compacting or tamping of several charges 56, S8 and 26 in the shell 22 under considerable pressure without collapsing the ash tube of relatively small Wall thickness. The outer shell 22, even if made of paper, will safely withstand considerable high-pressure tamping of the several charges therein. Thus, the instant cartridge with its metal ash tube readily lends itself to high-pressure tamping of the charges therein, either by hand or mechanically, assuring thereby that these charges have the required loading density and will settle no further until the cartridge is actually tired, and assuring further the desired duration of the cartridge arne. Of considerable importance in connection with the high-pressure tamping of the charges in the shell 22 is the instantclosed discharge end 60 of the flash tube 30 which throughout the considerable lengths of the radial fins 66 effectively block any penetration into the flash tube of particles of the more or less highly compacted ignition charge 26, especially when the closed discharge end of the llash tube has been further sealed with lacquer, as described.

The invention may be carried out in other speciic ways than those herein set forth Without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

We claim:

1. In an igniter cartridge having a shell with a head and a primer in the head, the combination of a slowburning powder base charge and an ignition charge in said shell of which the base charge is interposed between the shell head and ignition charge and has an internal passage through which the ash from the primer will pass directly to the ignition charge, and the latter is adapted to ignite said base charge; a closure for said shell; and an elongated insert of combustible metal extending in sai-d base charge substantially through the longitudinal expanse of the latter and adapted to be melted and carried off as globules by the ame from the fired cartridge.

2. The combination in an igniter cartridge as set forth in claim l, in which said insert is a metal tube disposed in said base charge substantially coaxially thereof.

3. The combination in an igniter cartridge as set forth in claim 1, in which said insert is a metal tube fitting in said passage in the base charge.

4. In an igniter cartridge having a shell with a head and a primer in the head, the combination of a slowburning powder base charge and an ignition charge in said shell of which the base charge is interposed between the shell head and ignition charge and has a longitudinal passage, and the ignition charge is adapted to ignite said base charge; a closure for said shell; and a ash tube in said shell extending from said primer through said passage in the base charge to the ignition charge for directing the primer ash directly to the latter, said ash tube being made of combustible metal and adapted to be melted and carried olf as globules by the flame from the iired cartridge.

5. The combination in an igniter cartridge as set forth in claim 4, in which the ash tube is at its end nearest said ignition charge closed for ready opening by the primer ash.

6. The combination in an igniter cartridge as set forth in claim 4, in which said base charge is in rm engagement with the outer periphery of said ash tube.

7. The combination in an igniter cartridge as set forth in claim 4, in which said ignition charge is also a powder charge, said flash tube is at its end nearest said ignition charge closed for ready opening by the primer flash, and both of said charges are compacted in the space between said shell and ash tube therein.

8. in an igniter cartridge having a shell with a head carrying a primer at one end and with a closure at the other end, the combination therein of a slow-burning base charge adjacent to the head; a fast-burning ignition charge adjacent to the closure; and a transition charge therebetween, said transition charge being a blend of the said ignition and base charges, and said base and transition charges having a longitudinal passage; and a ash tube extending in said passage from said primer to said ignition charge for directing the primer ilash directly to the latter, said flash tube being made of combustible metal and adapted to be melted and carried olf as globules by the ame from the fired cartridge.

9. In an igniter cartridge having a shell with a head carrying a primer on one end and with a closure at the other end, the combination therein of a slow-burning charge adjacent to the head; a fast-burning ignition charge adjacent to the closure; and a transition charge therebetween, said base and transition charges having a longitudinal passage extending from said primer to the ignition charge for directing the primer flash directly ot the latter, all of said charges having common constituents comprlsing magnesium powder and an oxidizing agent selected from the group consisting of the alkaline earth peroxides and nitrates, a fuel and a metal soap binder, the proportion of magnesium powder in each charge increasing progressively from the ignition to the transition to the base charge, while the proportion of said oxidizing agent 1n each of said charges decreases progressively in that same order.

10. In an igniter cartridge having a shell with a head and a primer in the head at one end of the cartridge and a closure at the other, the combination of successive rst, second and third charges in said shell of which the first charge is a slow-burning base charge and is nearest said shell head, said slow-burning base charge consisting of approximately 25 percent of magnesium powder, about 60 percent of an oxidizing agent selected from the group consisting of the alkaline earth peroxides and nitrates, the balance being a fuel and a metal soap binder; and said second and third charges are successively fast-burning transition and ignition charges which are composed of approximately percent and 20 percent, respectively, of the composition of said base charge, and about 20 percent and 8O percent, respectively, of a fast-burning ignition mixture consisting of about 15 percent of magnesium powder, with the balance consisting predominantly of an alkaline earth peroxide, all of said percentages being by weight; said flrst and second charges having a longitudinal passage extending from said primer to said third charge for directing the primer flash directly to the latter.

Holm Aug. 17, 1937 Johnson Feb. 17, 1948 

1. IN AN IGNITER CARTRIDGE HAVING A SHELL WITH HEAD AND A PRIMER IN THE HEAD, THE COMBINATION OF A SLOWBURNING POWDER BASE CHARGE IS INTERPOSED BETWEEN THE SHELL OF WHICH THE BASE CHARGE IS INTERPOSED BETWEEN THE SHELL HEAD AND IGNITION CHARGE AND HAS AN INTERNAL PASSAGE THROUGH WHICH THE FLASH FROM THE PRIMER WILL PASS DIRECTLY TO THE IGNITION CHARGE, AND THE LATTER IS ADAPTED TO IGNITE SAID BASE CHARGE; A CLOSURE FOR SAID SHELL; AND AN ELONGATED INSERT OF COMBUSTIBLE METAL EXTENDING IN SAID BASE CHARGE SUBSTANTIALLY THROUGH THE LONGITUDINAL EXPANSE OF THE LATTER AND ADAPTED TO BE MELTED AND CARRIED OFF AS GLOBULES BY THE FLAME FROM THE FIRED CARTRIDGE. 